1. Field of the Invention
The invention relates to a device for holding a fin-stabilized subcaliber projectile in relation to the casing of a telescoped ammunition round wherein the projectile is confined to the cartridge case.
2. Related Art Statement
Telescoped ammunition, which have given rise to many developments in the last few years, are characterized in that the projectile is disposed inside the cartridge case containing the grain charge instead of protruding outside of the latter.
Generally, the propellant charge is disposed around the projectile and gas-tightness problems arise. Since the projectile is not introduced into the barrel of a weapon when the round of ammunition is in the chamber; instead, it is the pressure due to the combustion of propellant charge gases which will first bring the projectile into position and hen push it inside the barrel.
It is unsatisfactory that, upon firing, combustion gases will precede the projectile before the latter has entered far enough into the barrel to ensure gas-tightness.
Complex solutions have been developed and most of them pertain to a plurality of propellant charges ignite successively as described, for example, in U.S. Pat. No. 4,802,415.
A simpler solution is proposed by U.S. Pat. No. 4,770,098 which describes a round of ammunition wherein a bushing of plastic material closes the fore section of the casing; this bushing of plastic material includes a hole the diameter of which is slightly smaller than that of a full-caliber round.
The sound is, therefore, immobilized by the bushing which thus ensures gas-tightness with respect to the propellant gas from the propellant charge.
However, such a concept will be interesting only if the size of the bushing does not excessively limit the volume reserved for the propellant charge.
For this concept to be applied to a round of ammunition wherein the projectile is of the fin-stabilized, subcaliber type and contained in a sabot, it is then necessary to design a sabot of the "drawer" type, which means that the resultant of the forces brought to bear on the sabot by propellant gases has an application point ahead of the projectile center of gravity.
As a matter of fact, the "full caliber" section of such a sabot will be located substantially in the nose of the projectile.
However, projectile driven by a drawer sabot are highly sensitive to transverse pressure waves and arms integral with the aft section of the sabot are required for guiding the projectile in the weapon barrel.
Such arms, the caliber of which is the same as that of the weapon, do not extend beyond the inner diameter of the bush and will not be capable of guiding the projectile in the round itself, if such a guidance is optical in the case of conventional rounds of ammunition wherein the fore section of the sabot is introduced into the weapon barrel, it becomes absolutely necessary for a telescoped round wherein a good introduction is conditioned by the control of the projectile trajectory in the round.
EP patent 0152492 describes a projectile with a tracer sabot wherein the fore section of the sabot projects outside the casing and is intended to enter into the weapon barrel. As the fore section of the projectile is in the weapon barrel as soon as the round is introduced, means for guiding the projectile in relation to the casing are thus useless.
Effectively, that patent shows arms located in the aft section of the sabot and guiding the projectile in the weapon barrel, but these arms cannot ensure guidance in relation to the casing of the round if the casing has a larger diameter than the weapon caliber.
U.S. Pat. No. 4,015,527 described a telescoped ammunition round of the same type as that shown in U.S. Pat. No. 4,802,415, namely including two distinct propellant.
The originality of the described arrangement lies in the presence of a sabot around the fins of the sub-projectile and fulfilling a gastightness function inside the casing of the round. With such an arrangement, the fin sabot is drawn into the weapon barrel and separates from the sub-projectile only after leaving the barrel, which may be detrimental to the sub-projectile stability.
U.S. Pat. No. 2,971,426 describes a loading process for an ammunition round comprising a fin-stabilized projectile.
In a second loading phase, the projectile is positioned in a tooling cylinder and a set ring is disposed at the location of the fins.
However, after installation of the projectile in the cartridge case, the rim of the set ring assumes a conical position which does not provide for the least positioning of the projectile in relation to the cartridge case.